[ben]

You can use most mics with these. I have used the 200 ohm ones and also the 600 ohm types without problems. Just adjust the mic level.

Note that the mic signal (in Rec or Amp mode) does not feed into the preamp outputl! So forget using the Tandberg as a mic amp. You'd have to use the speaker output I suppose, which would add a little more noise to the signal.

If you connect the 'Pre amp' phono socket to 'P. Up' and put the unit into 'AMP' you can mix a pre recorded tape with the 'live' mic, and accompany yourself - not sure if that'd be useful to you.

We have discussed these machines many times over the years. They were mostly used in education, and actually in production well into the 1980s - the later black ones bearing a TED sticker. I revived one last year.

Yours seems to be one of the earliest ones. You have the two track (half track) version. Note that in all these Tandberg 15s the rec/pb head is always stereo, the upper track is fed to the Free HD socket. You can connect this to a mic amplifier to play back the other side of the tape but you can only record in one direction at a time. So no overdubbing (you can do this on the 4 track/quarter track 15-41).

The main problem on these is the Rec/Amp switch which goes intermittent and crackly. I usually clean these with a q tip and rub the contacts with switch cleaner. just spraying rarely works for long.

Gummy grease on the linkages and joystick is another problem. I could write a book about all the work that needs doing on the really bad cases! If yours has been regularly used this should not be a problem.
I have a local industrial source for the drive belts for these. The originals tend to crack and fall apart. With a good belt the fast wind is very fast!
Fitting the belt is easy but there's a lot of dismantling needed of the top deck (knobs, head cover mounts, etc).
I have never needed to replace an electrolytic capacitor in these, but there is a Rifa one across the motor switch contacts on the transformer that should be changed before it shorts out!

The 24v VU meter bulb forms part of the oscillator and if it is blown you will get horrible interference.

Of all the mono units of the late 60s-early 70s,these are the most flexible and dependable. I have about half a dozen! Got one playing into the PC as we type.